Implement null video source.

git-svn-id: file:///var/local/repositories/ffmpeg/trunk@21240 9553f0bf-9b14-0410-a0b8-cfaf0461ba5b

doc/libavfilter.texi

@@ -197,4 +197,20 @@ Flip the input video vertically.
 ./ffmpeg -i in.avi -vfilters "vflip" out.avi
 @end example
 
+@chapter Available video sources
+
+Below is a description of the currently available video sources.
+
+@section nullsrc
+
+Null video source, never return images. It is mainly useful as a
+template and to be employed in analysis / debugging tools.
+
+It accepts as optional parameter a string of the form
+``width:height'', where ``width'' and ``height'' specify the size of
+the configured source.
+
+The default values of ``width'' and ``height'' are respectively 352
+and 288 (corresponding to the CIF size format).
+
 @bye

libavfilter/Makefile

@@ -20,4 +20,6 @@ OBJS-$(CONFIG_SCALE_FILTER)                  += vf_scale.o
 OBJS-$(CONFIG_SLICIFY_FILTER)                += vf_slicify.o
 OBJS-$(CONFIG_VFLIP_FILTER)                  += vf_vflip.o
 
+OBJS-$(CONFIG_NULLSRC_FILTER)                += vsrc_nullsrc.o
+
 include $(SUBDIR)../subdir.mak

libavfilter/allfilters.c

@@ -41,4 +41,6 @@ void avfilter_register_all(void)
     REGISTER_FILTER (SCALE, scale, vf);
     REGISTER_FILTER (SLICIFY, slicify, vf);
     REGISTER_FILTER (VFLIP, vflip, vf);
+
+    REGISTER_FILTER (NULLSRC, nullsrc, vsrc);
 }

libavfilter/avfilter.h

@@ -25,7 +25,7 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  1
-#define LIBAVFILTER_VERSION_MINOR 15
+#define LIBAVFILTER_VERSION_MINOR 16
 #define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \

libavfilter/vsrc_nullsrc.c

+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+/**
+ * @file libavfilter/vsrc_nullsrc.c
+ * null video source
+ */
+
+#include "avfilter.h"
+
+typedef struct {
+    int w, h;
+} NullContext;
+
+static int init(AVFilterContext *ctx, const char *args, void *opaque)
+{
+    NullContext *priv = ctx->priv;
+
+    priv->w = 352;
+    priv->h = 288;
+
+    if (args)
+        sscanf(args, "%d:%d", &priv->w, &priv->h);
+
+    if (priv->w <= 0 || priv->h <= 0) {
+        av_log(ctx, AV_LOG_ERROR, "Non-positive size values are not acceptable.\n");
+        return -1;
+    }
+
+    return 0;
+}
+
+static int config_props(AVFilterLink *outlink)
+{
+    NullContext *priv = outlink->src->priv;
+
+    outlink->w = priv->w;
+    outlink->h = priv->h;
+
+    av_log(outlink->src, AV_LOG_INFO, "w:%d h:%d\n", priv->w, priv->h);
+
+    return 0;
+}
+
+static int request_frame(AVFilterLink *link)
+{
+    return -1;
+}
+
+AVFilter avfilter_vsrc_nullsrc = {
+    .name        = "nullsrc",
+    .description = "Null video source, never return images.",
+
+    .init       = init,
+    .priv_size = sizeof(NullContext),
+
+    .inputs    = (AVFilterPad[]) {{ .name = NULL}},
+
+    .outputs   = (AVFilterPad[]) {
+        {
+            .name            = "default",
+            .type            = CODEC_TYPE_VIDEO,
+            .config_props    = config_props,
+            .request_frame   = request_frame,
+        },
+        { .name = NULL}
+    },
+};